Many children and adolescents with mental health problems do not receive the treatment they need. Unmet need raises questions about specific barriers that may prevent service use, and/or the characteristics of children and families who are less likely to receive care. Brief interventions or single-session psychotherapy delivered in a highly accessible manner are methods of addressing the problems associated with waitlists and limited access to care. In the current study the authors offer an exploratory evaluation of the West End Walk-In Counseling Centre for children and youth with psychosocial problems. Children 4 to 18 years of age who accessed the Walk-In Counseling Centre and a comparison group of clients who accessed usual care were assessed at intake, post-treatment, and 3-month follow-up on demographic characteristics, behavioral/emotional adjustment and functioning, client satisfaction, and service use. Children in the walk-in group had more severe behavioral/emotional adjustment and functioning than usual care clients at baseline. At post-treatment, walk-in clients had lower scores on Total Mental Health Problems and Internalizing Behaviors, and exhibited fewer problems across all scales at follow-up. Walk-in clients found the wait time for service more reasonable and at follow-up, felt the service addressed concerns and had higher regard for counselor availability and cultural sensitivity of the service than usual care clients. Service utilization, assessed at post-treatment and 3-month follow-up, showed that both groups were more likely to access mental health and education services rather than health or child welfare services, and were more likely to have used services in the 12 months prior to service than the 3 months following service completion. Walk-in clients had steeper rates of improvement compared to usual care clients despite equivalence in psychosocial functioning at baseline. The walk-in model may be an effective alternative to usual care, particularly for those clients only willing to wait up to 2 weeks for service.